465 lines
10 KiB
Prolog
465 lines
10 KiB
Prolog
/*************************************************************************
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* *
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* YAP Prolog *
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* *
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* Yap Prolog was developed at NCCUP - Universidade do Porto *
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* *
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* Copyright L.Damas, V.S.Costa and Universidade do Porto 1985-1997 *
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* *
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**************************************************************************
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* *
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* File: yio.yap *
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* Last rev: *
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* mods: *
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* comments: Input output predicates *
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* *
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*************************************************************************/
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:- system_module( '$_yio', [at_end_of_line/0,
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at_end_of_line/1,
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consult_depth/1,
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current_char_conversion/2,
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current_line_number/1,
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current_line_number/2,
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current_stream/3,
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display/1,
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display/2,
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exists/1,
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fileerrors/0,
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format/1,
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nofileerrors/0,
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open_pipe_streams/2,
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prolog_file_name/2,
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read/1,
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read/2,
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sformat/3,
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socket/2,
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socket/4,
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socket_connect/3,
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stream_position/2,
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stream_position/3,
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stream_position_data/3,
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ttyget/1,
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ttyget0/1,
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ttynl/0,
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ttyput/1,
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ttyskip/1,
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rename/2,
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write_depth/2], ['$default_expand'/1,
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'$extend_file_search_path'/1,
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'$set_default_expand'/1]).
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:- use_system_module( '$_boot', ['$system_catch'/4]).
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:- use_system_module( '$_errors', ['$do_error'/2]).
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/** @defgroup InputOutput Input/Output Predicates
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@ingroup builtins
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Some of the Input/Output predicates described below will in certain conditions
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provide error messages and abort only if the file_errors flag is set.
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If this flag is cleared the same predicates will just fail. Details on
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setting and clearing this flag are given under 7.7.
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@{
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*/
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/* stream predicates */
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/** @defgroup IO_Sockets YAP Old Style Socket and Pipe Interface
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@{
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Autoload the socket/pipe library
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*/
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/** @pred socket(+ _DOMAIN_,- _SOCKET_)
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Call socket/4 with _TYPE_ bound to `SOCK_STREAM'` and
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_PROTOCOL_ bound to `0`.
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*/
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/** @pred socket(+ _DOMAIN_,+ _TYPE_,+ _PROTOCOL_,- _SOCKET_)
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Corresponds to the BSD system call `socket`. Create a socket for
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domain _DOMAIN_ of type _TYPE_ and protocol
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_PROTOCOL_. Both _DOMAIN_ and _TYPE_ should be atoms,
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whereas _PROTOCOL_ must be an integer.
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The new socket object is
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accessible through a descriptor bound to the variable _SOCKET_.
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The current implementation of YAP accepts socket
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domains `AF_INET` and `AF_UNIX`.
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Socket types depend on the
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underlying operating system, but at least the following types are
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supported: `SOCK_STREAM'` and `SOCK_DGRAM'` (untested in 6.3).
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*/
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/** @pred socket_connect(+ _SOCKET_, + _PORT_, - _STREAM_)
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Interface to system call `connect`, used for clients: connect
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socket _SOCKET_ to _PORT_. The connection results in the
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read/write stream _STREAM_.
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Port information depends on the domain:
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+ 'AF_UNIX'(+ _FILENAME_)
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+ 'AF_FILE'(+ _FILENAME_)
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connect to socket at file _FILENAME_.
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+ 'AF_INET'(+ _HOST_,+ _PORT_)
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Connect to socket at host _HOST_ and port _PORT_.
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*/
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/** @pred open_pipe_streams(Read, Write)
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Autoload old pipe access interface
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*/
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%! @}
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/** @pred exists(+ _F_)
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Checks if file _F_ exists in the current directory.
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*/
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exists(F) :-
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absolute_file_name(F, _, [file_errors(fail),access(exist),expand(true)]).
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%! @addtogroup ReadTerm
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% @{
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/* Term IO */
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%! @}
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%! @addtogroup Write
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% @{
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/* meaning of flags for '$write' is
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1 quote illegal atoms
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2 ignore operator declarations
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4 output '$VAR'(N) terms as A, B, C, ...
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8 use portray(_)
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flags are defined in yapio.h
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*/
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/** @pred display(+ _T_)
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Displays term _T_ on the current output stream. All Prolog terms are
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written in standard parenthesized prefix notation.
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*/
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display(T) :-
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current_output(Out),
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write_term(Out, T, [ignore_ops(true)]).
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/** @pred display(+ _S_, _T_)
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Like display/1, but using stream _S_ to display the term.
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*/
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display(Stream, T) :-
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write_term(Stream, T, [ignore_ops(true)]).
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/* interface to user portray */
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'$portray'(T) :-
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\+ '$undefined'(portray(_),user),
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'$system_catch'(call(portray(T)),user,Error,user:'$Error'(Error)), !,
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set_value('$portray',true), fail.
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'$portray'(_) :- set_value('$portray',false), fail.
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%! @}
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%! @addtogroup Format
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% @{
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/** @pred format(+ _T_)
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Print formatted output to the current output stream.
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*/
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format(T) :-
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format(T, []).
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%! @}
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%! @addtogroup CharsIO
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% @{
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/* character I/O */
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/** @pred ttyget(- _C_)
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The same as `get(C)`, but from stream user_input.
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*/
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ttyget(N) :- get(user_input,N).
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/** @pred ttyget0(- _C_)
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The same as `get0(C)`, but from stream user_input.
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*/
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ttyget0(N) :- get0(user_input,N).
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/** @pred ttyskip(- _C_)
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Like skip/1, but always using stream user_input.
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stream.
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*/
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ttyskip(N) :- N1 is N, '$skip'(user_input,N1).
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/** @pred ttyput(+ _N_)
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As `put(N)` but always to user_output.
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*/
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ttyput(N) :- N1 is N, put(user_output,N1).
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/** @pred ttynl
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Outputs a new line to stream user_output.
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*/
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ttynl :- nl(user_output).
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%! @}
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%! @addtogroup StreamM
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% @{
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/** @pred current_line_number(- _LineNumber_)
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Unify _LineNumber_ with the line number for the current output stream.
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*/
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current_line_number(N) :-
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current_input(Stream),
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line_count(Stream, N).
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/** @pred current_line_number(+ _Stream_,- _LineNumber_)
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Unify _LineNumber_ with the line number for _Stream_.
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*/
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current_line_number(Stream,N) :-
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line_count(Stream, N).
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/** @pred stream_position(+ _Stream_,- _StreamPosition_)
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Unify _StreamPosition_ with the packaged information of position on
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current stream _Stream_. Use stream_position_data/3 to
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retrieve information on character or line count.
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*/
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stream_position(Stream, Position) :-
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stream_property(Stream, position(Position)).
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/** @pred stream_position(+ _Stream_,- _StreamPosition_, +_NewPosition_)
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Unify _StreamPosition_ with the packaged information of position on
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current stream _Stream_ an then moves to position _NewPosition_.
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*/
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stream_position(Stream, Position, NewPosition) :-
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stream_property(Stream, position(Position)),
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set_stream_position(Stream, NewPosition).
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/** @pred at_end_of_line
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Tests whether the next character in the current input stream is a line break character.
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*/
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at_end_of_line :-
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current_input(S),
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at_end_of_line(S).
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/** @pred at_end_of_line( +Stream )
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Tests whether the next character in the stream is a line break character.
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*/
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at_end_of_line(S) :-
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stream_property(S, end_of_stream(past)), !.
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at_end_of_line(S) :-
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peek_code(S,N), ( N = 10 -> true ; N = -1).
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/** @pred current_char_conversion(? _IN_,? _OUT_) is iso
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If _IN_ is unbound give all current character
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translations. Otherwise, give the translation for _IN_, if one
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exists.
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*/
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current_char_conversion(X,Y) :-
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var(X), !,
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'$all_char_conversions'(List),
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'$fetch_char_conversion'(List,X,Y).
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current_char_conversion(X,Y) :-
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'$current_char_conversion'(X,Y).
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'$fetch_char_conversion'([X,Y|_],X,Y).
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'$fetch_char_conversion'([_,_|List],X,Y) :-
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'$fetch_char_conversion'(List,X,Y).
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split_path_file(File, Path, Name) :-
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file_directory_name(File, Path),
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file_base_name(File, Name).
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/** @pred current_stream( _F_, _M_, _S_)
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Defines the relation: The stream _S_ is opened on the file _F_
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in mode _M_. It might be used to obtain all open streams (by
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backtracking) or to access the stream for a file _F_ in mode
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_M_, or to find properties for a stream _S_. Notice that some
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streams might not be associated to a file: in this case YAP tries to
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return the file number. If that is not available, YAP unifies _F_
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with _S_.
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*/
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current_stream(File, Mode, Stream) :-
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stream_property(Stream, mode(Mode)),
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'$stream_name'(Stream, File).
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'$stream_name'(Stream, File) :-
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stream_property(Stream, file_name(File)), !.
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'$stream_name'(Stream, file_no(File)) :-
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stream_property(Stream, file_no(File)), !.
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'$stream_name'(Stream, Stream).
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'$extend_file_search_path'(P) :-
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atom_codes(P,S),
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'$env_separator'(ES),
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'$split_for_path'(S,0'=,ES,Paths), %'
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'$add_file_search_paths'(Paths).
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'$split_for_path'([], _, _, []).
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'$split_for_path'(S, S1, S2, [A1=A2|R]) :-
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'$fetch_first_path'(S, S1, A1, SR1),
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'$fetch_second_path'(SR1, S2, A2, SR),
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'$split_for_path'(SR, S1, S2, R) .
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'$fetch_first_path'([S1|SR],S1,[],SR) :- !.
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'$fetch_first_path'([C|S],S1,[C|F],SR) :-
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'$fetch_first_path'(S,S1,F,SR).
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'$fetch_second_path'([],_,[],[]).
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'$fetch_second_path'([S1|SR],S1,[],SR) :- !.
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'$fetch_second_path'([C|S],S1,[C|A2],SR) :-
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'$fetch_second_path'(S,S1,A2,SR).
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'$add_file_search_paths'([]).
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'$add_file_search_paths'([NS=DS|Paths]) :-
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atom_codes(N,NS),
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atom_codes(D,DS),
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assert(user:file_search_path(N,D)),
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'$add_file_search_paths'(Paths).
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'$format@'(Goal,Out) :-
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with_output_to(codes(Out), Goal).
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sformat(String, Form, Args) :-
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format(codes(String, []), Form, Args).
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/** @pred stream_position_data(+ _Field_,+ _StreamPosition_,- _Info_)
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Extract values from stream position objects.
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'$stream_position' is of the format '$stream_position'(Byte, Char,
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Line, LinePos). Given the packaged stream position term
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_StreamPosition_, unify _Info_ with _Field_ `line_count`,
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`byte_count`, or `char_count`.
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*/
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stream_position_data(Prop, Term, Value) :-
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nonvar(Prop), !,
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( '$stream_position_field'(Prop, Pos)
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-> arg(Pos, Term, Value)
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; '$do_error'(domain_error(stream_position_data), Prop)
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).
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stream_position_data(Prop, Term, Value) :-
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'$stream_position_field'(Prop, Pos),
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arg(Pos, Term, Value).
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'$stream_position_field'(char_count, 1).
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'$stream_position_field'(line_count, 2).
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'$stream_position_field'(line_position, 3).
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'$stream_position_field'(byte_count, 4).
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'$set_encoding'(Enc) :-
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set_stream(loop_stream, encoding(Enc)).
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%! @}
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'$codes_to_chars'(String0, String, String0) :- String0 == String, !.
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'$codes_to_chars'(String0, [Code|String], [Char|Chars]) :-
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atom_codes(Char, [Code]),
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'$codes_to_chars'(String0, String, Chars).
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/** @pred file_exists(+ _File__)
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The atom _File_ corresponds to an existing file or directory.
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*/
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file_exists(IFile) :-
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absolute_file_name(IFile, _File, [expand(true), solutions(first), access(exist)]).
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/** @pred rename(+F , +G)
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Renames the single file _F_ to _G_.
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*/
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rename(IFile, OFile) :-
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absolute_file_name(IFile, IF, [access(read),expand(true)]),
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absolute_file_name(OFile, OF, [expand(true)]),
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'$rename'(IF, OF).
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/** @pred access_file(+F , +G)
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Verify whether file F respects property _G_. The file is processed
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with absolute_file_name.
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*/
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access_file(IFile, Access) :-
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absolute_file_name(IFile, _IF, [access(Access),expand(true)]).
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/**
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@}
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*/
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